Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “braided composite”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

A Modeling Technique and Representation of Failure in the Analysis of Triaxial Braided Carbon Fiber Composites

Quasi-static tests have been performed on triaxially braided carbon fiber composite materials with large unit cell sizes. The effects of different fibers and matrix materials on the failure mode were investigated. Simulations of the tests have been performed using the transient dynamic finite element code, LS-DYNA. However, the wide range of failure modes observed for the triaxial braided carbon fiber composites during tests could not be simulated using composite material models currently available within LS-DYNA. A macroscopic approach has been developed that provides better simulation of the material response in these materials. This approach uses full-field optical measurement techniques to measure local failures during quasi-static testing. Information from these experiments is then used along with the current material models available in LS-DYNA to simulate the influence of the braided architecture on the failure process. This method uses two-dimensional shell elements with integration points through the thickness of the elements to represent the different layers of braid along with a new analytical method for the import of material stiffness and failure data directly. The present method is being used to examine the effect of material properties on the failure process. The experimental approaches used to obtain the required data will be described, and preliminary results of the numerical analysis will be presented.

Littell, Justin D.↗
NASA NTRS1992

Development of generalized 3-D braiding machines for composite preforms

The development of prototype braiding machines for the production of generalized braid patterns is described. Mechanical operating principles and control strategies are presented for two prototype machines which have been fabricated and evaluated. Both machines represent advances over current fabrication techniques for composite materials by enabling nearly ideal control of fiber orientations within preform structures. They permit optimum design of parts that might be subjected to complex loads or that have complex forms. Further, they overcome both the lack of general control of produced fiber architectures and the complexity of other weaving processes that have been proposed for the same purpose. One prototype, the Farley braider, consists of an array of turntables that can be made to oscillate in 90 degree steps. Yarn ends are transported about the surface formed by the turntables by motorized tractors which are controlled through an optical link with the turntables and powered through electrical contact with the turntables. The necessary relative motions are produced by a series of linear tractor moves combined with a series of turntable rotations. As the tractors move about, they weave the yarn ends into the desired pattern. The second device, the shuttle plate braider, consists of a braiding surface formed by an array of stationary square sections, each separated from its neighbors by a gap. A plate beneath this surface is caused to reciprocate in two perpendicular directions, first in one direction and then in the other. This movement is made possibly by openings in the plate that clear short columns supporting the surface segments. Yarn ends are moved about the surface and interwoven by shuttles which engage the reciprocating plate as needed to yield the desired movements. Power and control signals are transmitted to the shuttles through electrical contact with the braiding surface. The shuttle plate is a passively driven prime mover that supplies the power to move all shuttles and the shuttles are simple devices that employ only a solenoid to engage the shuttle plate on command. Each shuttle is assigned a unique identity and is controlled independently. When compared to each other, the Farley braider is felt to have the advantage of speed and the shuttle plate braider, the advantage of simplicity.

Huey, Cecil O., Jr.↗
NASA NTRS1995

Braiding And Wrapping Tape To Make A Composite Vessel

Braiding and forming combined in one-step process. In process, continuous plus or minus 45 degrees bias braided tape fabricated. Braiding done on site, and braided tape immediately wound on male mandrel in shinglelike configuration to make fabric preform. Subsequently, preform impregnated with matrix resin. Improved process does not produce stitches. Expected to yield consistent quality, to involve less handling of fabric, to produce less scrap, and thus to cost less.

Freitas, Glenn↗
NASA NTRS2013

Weight Assessment for Fuselage Shielding on Aircraft With Open-Rotor Engines and Composite Blade Loss

The Federal Aviation Administration (FAA) has been engaged in discussions with airframe and engine manufacturers concerning regulations that would apply to new technology fuel efficient "openrotor" engines. Existing regulations for the engines and airframe did not envision features of these engines that include eliminating the fan blade containment systems and including two rows of counter-rotating blades. Damage to the airframe from a failed blade could potentially be catastrophic. Therefore the feasibility of using aircraft fuselage shielding was investigated. In order to establish the feasibility of this shielding, a study was conducted to provide an estimate for the fuselage shielding weight required to provide protection from an open-rotor blade loss. This estimate was generated using a two-step procedure. First, a trajectory analysis was performed to determine the blade orientation and velocity at the point of impact with the fuselage. The trajectory analysis also showed that a blade dispersion angle of 3deg bounded the probable dispersion pattern and so was used for the weight estimate. Next, a finite element impact analysis was performed to determine the required shielding thickness to prevent fuselage penetration. The impact analysis was conducted using an FAA-provided composite blade geometry. The fuselage geometry was based on a medium-sized passenger composite airframe. In the analysis, both the blade and fuselage were assumed to be constructed from a T700S/PR520 triaxially-braided composite architecture. Sufficient test data on T700S/PR520 is available to enable reliable analysis, and also demonstrate its good impact resistance properties. This system was also used in modeling the surrogate blade. The estimated additional weight required for fuselage shielding for a wing- mounted counterrotating open-rotor blade is 236 lb per aircraft. This estimate is based on the shielding material serving the dual use of shielding and fuselage structure. If the shielding material is not used for dual purpose, and is only used for shielding, then the additional weight per aircraft is estimated to be 428 lb. This weight estimate is based upon a number of assumptions that would need to be revised when applying this concept to an actual airplane design. For example, the weight savings that will result when there is no fan blade containment system, manufacturing limitations which may increase the weight where variable thicknesses was assumed, engine placement on the wing versus aft fuselage, etc.

aircraft safety↗
NASA NTRS1988

Composite materials: Testing and design

The present conference discusses topics in the analysis of composite structures, composite materials' impact and compression behavior, composite materials characterization methods, composite failure mechanisms, NDE methods for composites, and filament-wound and woven composite materials' fabrication. Attention is given to the automated design of a composite plate for damage tolerance, the effects of adhesive layers on composite laminate impact damage, instability-related delamination growth in thermoset and thermoplastic composites, a simple shear fatigue test for unidirectional E-glass epoxy, the growth of elliptic delaminations in laminates under cyclic transverse shear, and the mechanical behavior of braided composite materials.

Whitcomb, John D.↗
NASA NTRS1995

TEXCAD: TEXile Composite Analysis for Design

The Textile Composite Analysis for Design (TEXCAD) code provides the materials/design engineer with a user-friendly, desktop computer based tool for the analysis of a wide variety of fabric reinforced woven and braided composites. It can be used to calculate overall thermal and mechanical properties along with engineering estimates of damage progression and strength. TEXCAD also calculates laminate properties for stacked, oriented fabric constructions. It discretely models the yarn centerline paths within the textile repeating unit cell (RUC) by assuming sinusoidal undulations at yarn cross-over points and uses a year discretization scheme (which subdivides each yarn into smaller, piecewise straight yarn slices) together with a 3-D stress averaging procedure to compute overall stiffness properties. In the calculations for strength, it uses a curved beam-on-elastic foundation model for yarn undulating regions together with incremental approach in which stiffness properties for the failed yarn slices are reduced based on the predicted yarn slice failure mode. Nonlinear shear effects and nonlinear geometric effects can be stimulated. Input to TEXCAD consists of: (1) material parameters like impregnated yarn and resin properties such as moduli, Poisson's ratios, coefficients of thermal expansion, nonlinear shear parameters, axial failure strains, and in-plane failure stresses; and (2) fabric parameters like yarn sizes, braid angle, yarn packing density, filament diameter, and overall fiber volume fraction. Output consists of overall thermoelastic constants, yarn slice strains/stresses, yarn slice failure history, in-plane strain response, and ultimate failure strength. Strength can be computed under the combined action of thermal and mechanical loading (tension, compression, and shear). A brief overview of the analytical capabilities, program organization, and modules, input and output parameters, computer platforms, distribution, and modifications/extensions of the TEXCAD code are presented here.

Naik, Rajiv A.↗
NASA NTRS1994

TEXCAD: Textile Composite Analysis for Design. Version 1.0: User's manual

The Textile Composite Analysis for Design (TEXCAD) code provides the materials/design engineer with a user-friendly desktop computer (IBM PC compatible or Apple Macintosh) tool for the analysis of a wide variety of fabric reinforced woven and braided composites. It can be used to calculate overall thermal and mechanical properties along with engineering estimates of damage progression and strength. TEXCAD also calculates laminate properties for stacked, oriented fabric constructions. It discretely models the yarn centerline paths within the textile repeating unit cell (RUC) by assuming sinusoidal undulations at yarn cross-over points and uses a yarn discretization scheme (which subdivides each yarn not smaller, piecewise straight yarn slices) together with a 3-D stress averaging procedure to compute overall stiffness properties. In the calculations for strength, it uses a curved beam-on-elastic foundation model for yarn undulating regions together with an incremental approach in which stiffness properties for the failed yarn slices are reduced based on the predicted yarn slice failure mode. Nonlinear shear effects and nonlinear geometric effects can be simulated. Input to TEXCAD consists of: (1) materials parameters like impregnated yarn and resin properties such moduli, Poisson's ratios, coefficients of thermal expansion, nonlinear parameters, axial failure strains and in-plane failure stresses; and (2) fabric parameters like yarn sizes, braid angle, yarn packing density, filament diameter and overall fiber volume fraction. Output consists of overall thermoelastic constants, yarn slice strains/stresses, yarn slice failure history, in-plane stress-strain response and ultimate failure strength. Strength can be computed under the combined action of thermal and mechanical loading (tension, compression and shear).

Naik, Rajiv A.↗
NASA NTRS1993

Development of generalized 3-D braiding machines for composite preforms

The operating principles of two prototype braiding machines for the production of generalized braid patterns are described. Both processes afford previously unachievable control of the interlacing of fibers within a textile structure that make them especially amenable to the fabrication of textile preforms for composite materials. They enable independent control of the motion of the individual fibers being woven, thereby enabling the greatest possible freedom in controlling fiber orientation within a structure. This freedom enables the designer to prescribe local fiber orientation to better optimize material performance. The processes have been implemented on a very small scale but at a level that demonstrates their practicality and the soundness of the principles governing their operation.

Huey, Cecil O., Jr.↗
NASA NTRS2014

An Overview of SBIR Phase 2 Airbreathing Propulsion Technologies

Technological innovation is the overall focus of NASA's Small Business Innovation Research (SBIR) program. The program invests in the development of innovative concepts and technologies to help NASA's mission directorates address critical research and development needs for agency projects. This report highlights innovative SBIR Phase II projects from 2007-2012 specifically addressing areas in Airbreathing Propulsion which is one of six core competencies at NASA Glenn Research Center. There are twenty technologies featured with emphasis on a wide spectrum of applications such as with a Turbo-Brayton cryocooler for aircraft superconducting systems, braided composite rotorcraft structures, engine air brake, combustion control valve, flexible composite driveshaft, and much more. Each article in this booklet describes an innovation, technical objective, and highlights NASA commercial and industrial applications. This report serves as an opportunity for NASA personnel including engineers, researchers, and program managers to learn of NASA SBIR's capabilities that might be crosscutting into this technology area. As the result, it would cause collaborations and partnerships between the small companies and NASA Programs and Projects resulting in benefit to both SBIR companies and NASA.

Nguyen, Hung D.↗
NASA NTRS1997

Development of Stitched, Braided and Woven Composite Structures in the ACT Program and at Langley Research Center

Summary results are presented from the research conducted on woven, braided, knitted and stitched (textile) composites at the Langley Research Center and under the NASA Advanced Composites Technology (ACT) Program in the period from 1985 to 1997. The report also includes an annotated bibliography of 270 U.S. publications on textile composites (with their abstracts). Two major research areas are discussed: (1) the general research in textile composites performed throughout the period under the direction of the Langley Research Center and (2) the development of textile composite aircraft structures by industry under the NASA ACT Program. The annotated bibliography is organized in three subsections: (1) general textiles R&D under the auspices of Langley, (2) ACT Program development of textile structural components, and (3) textiles research by individuals and organizations not associated with the ACT Program. An author index is provided for the reports and documents.

Dow, Marvin B.↗
NASA NTRS1992

Modeling of Euclidean braided fiber architectures to optimize composite properties

Three-dimensional braided fiber reinforcements are a very effective toughening mechanism for composite materials. The integral yarn path inherent to this fiber architecture allows for effective multidirectional dispersion of strain energy and negates delamination problems. In this paper a geometric model of Euclidean braid fiber architectures is presented. This information is used to determine the degree of geometric isotropy in the braids. This information, when combined with candidate material properties, can be used to quickly generate an estimate of the available load-carrying capacity of Euclidean braids at any arbitrary angle.

Armstrong-Carroll, E.↗
NASA NTRS2018

Influence of Fiber Volume and Alignment on Impact Resistance of Braided Carbon Fiber Epoxy Composites

The effect of axial tow alignment within a laminate ply stack on the impact penetration threshold for a series of composite panels was evaluated; specifically, the effect of a lateral shift in alignment to induce fiber nesting. Panels were fabricated from braided T700S carbon fiber and TenCate Advanced Composites's TC275-1 epoxy resin prepreg. Axial tows in each ply were aligned, offset, or rotated to evaluate the influence of such parameters on impact penetration resistance. Panel-to-panel variation in thickness, resin content, and fiber volume ratio were measured. Ultimately, process-related deviations drove penetration limits on impact. Influence of axial tow alignment was difficult to discern outside of the processing-induced variations between panels.

process variation↗
NASA NTRS2007

In-Plane Cracking Behavior and Ultimate Strength for 2D Woven and Braided Melt-Infiltrated SiC/SiC Composites Tensile Loaded in Off-Axis Fiber Directions

The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for architectural design of CMC components that are subjected to multi-axial stress states. In this study, 2D-woven melt-infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0 degree and 90 degree directions were tensile loaded in-plane in the 0 degree direction and at 45 degree to this direction. In addition, a 2D triaxially-braided MI composite panel with balanced fiber content in the plus or minus 67 degree bias directions and reduced fiber content in the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23 degrees from the bias fibers). Stress-strain behavior, acoustic emission, and optical microscopy were used to quantify stress-dependent matrix cracking and ultimate strength in the panels. It was observed that both off-axis loaded panels displayed higher composite onset stresses for through-thickness matrix cracking than the 2D-woven 0/90 panels loaded in the primary 0 degree direction. These improvements for off-axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on critical matrix flaws for a given composite stress. Also for the 0/90 panel loaded in the 45 degree direction, an improved distribution of matrix flaws existed due to the absence of fiber tows perpendicular to the loading direction. In addition, for the +67/0/-67 braided panel, the axial tows perpendicular to the loading direction were not only low in volume fraction, but were also were well separated from one another. Both off-axis oriented panels also showed relatively good ultimate tensile strength when compared to other off-axis oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial implications are discussed for constituent and architecture design to improve the directional cracking of SiC/SiC CMC components with MI matrices.

Morscher, Gregory N.↗
NASA NTRS1993

Three-dimensional analysis of anisotropic spatially reinforced structures

The material-adaptive three-dimensional analysis of inhomogeneous structures based on the meso-volume concept and application of deficient spline functions for displacement approximations is proposed. The general methodology is demonstrated on the example of a brick-type mosaic parallelepiped arbitrarily composed of anisotropic meso-volumes. A partition of each meso-volume into sub-elements, application of deficient spline functions for a local approximation of displacements and, finally, the use of the variational principle allows one to obtain displacements, strains, and stresses at anypoint within the structural part. All of the necessary external and internal boundary conditions (including the conditions of continuity of transverse stresses at interfaces between adjacent meso-volumes) can be satisfied with requisite accuracy by increasing the density of the sub-element mesh. The application of the methodology to textile composite materials is described. Several numerical examples for woven and braided rectangular composite plates and stiffened panels under transverse bending are considered. Some typical effects of stress concentrations due to the material inhomogeneities are demonstrated.

Bogdanovich, Alexander E.↗
NASA NTRS2015

Design, Fabrication, and Testing of a Composite Rack Prototype in Support of the Deep Space Habitat Program

In support of the Deep Space Habitat project a number of composite rack prototypes were developed, designed, fabricated and tested to various extents ( with the International Standard Payload Rack configuration, or crew quarters, as a baseline). This paper focuses specifically on a composite rack prototype with a direct tie in to Space Station hardware. The outlined prototype is an all composite construction, excluding metallic fasteners, washers, and their associated inserts. The rack utilizes braided carbon composite tubing for the frame with the sidewalls, backwall and flooring sections utilizing aircraft grade composite honeycomb sandwich panels. Novel additively manufactured thermoplastic joints and tube inserts were also developed in support of this effort. Joint and tube insert screening tests were conducted at a preliminary level. The screening tests allowed for modification, and enhancement, of the fabrication and design approaches, which will be outlined. The initial joint tests did not include mechanical fasteners. Adhesives were utilized at the joint to composite tube interfaces, along with mechanical fasteners during final fabrication (thus creating a stronger joint than the adhesive only variant). In general the prototype was focused on a potential in-space assembly approach, or kit-of-parts construction concept, which would not necessarily require the inclusion of an adhesive in the joint regions. However, given the tie in to legacy Station hardware (and potential flight loads with imbedded hardware mass loadings), the rack was built as stiff and strong as possible. Preliminary torque down tests were also conducted to determine the feasibility of mounting the composite honeycomb panels to the composite tubing sections via the additively manufactured tube inserts. Additional fastener torque down tests were also conducted with inserts (helicoils) imbedded within the joints. Lessons learned are also included and discussed.

Smith, Russ↗
NASA NTRSDate not supplied

Crash Sled Testing of Triaxially-Braided CFRP for Improved Vehicular Crashworthiness

The Impact Dynamics Laboratory at NASA Glenn Research Center recently developed a pneumatically-actuated crash sled for investigating the crush behavior of structural elements for vehicular applications. The apparatus includes an adjustable striker mass and specimen support mass, which are mounted on separate rails. This setup provides two advantages over crash sleds with so-called fixed specimen supports: (i) it allows for multiple independent measurements of the crush response using different instruments, and (ii) the specimen support can be varied and its reaction can be explicitly measured. This paper describes the experimental setup and data analysis methodology and illustrates the capability of the sled for measuring the specific energy absorption (SEA) of triaxially-braided carbon/epoxy composite C-channels and corrugated plates. The corrugated plate had a higher SEA than the C-channel and the SEAs did not vary when the striker mass and velocity were changed so that incident energy was constant.

Charles R Ruggeri↗
NASA NTRS2020

Crash Sled Testing of Triaxially-Braided CFRP for Improved Vehicular Crashworthiness

The Impact Dynamics Laboratory at NASA Glenn Research Center recently developed a pneumatically-actuated crash sled for investigating the crush behavior of structural elements for vehicular applications. The apparatus includes an adjustable striker mass and specimen support mass, which are mounted on separate rails. This setup provides two advantages over crash sleds with so-called fixed specimen supports: (i) it allows for multiple independent measurements of the crush response using different instruments, and (ii) the specimen support can be varied and its reaction can be explicitly measured. This paper describes the experimental setup and data analysis methodology and illustrates the capability of the sled for measuring the specific energy absorption (SEA) of triaxially-braided carbon/epoxy composite C-channels and corrugated plates. The corrugated plate had a higher SEA than the C-channel and the SEAs did not vary when the striker mass and velocity were changed so that incident energy was constant.

Composite Material↗
NASA NTRSDate not supplied

Crash Sled Testing of Triaxially-Braided CFRP for Improved Vehicular Crashworthiness

The Impact Dynamics Laboratory at NASA Glenn Research Center recently developed a pneumatically-actuated crash sled for investigating the crush behavior of structural elements for vehicular applications. The apparatus includes an adjustable striker mass and specimen support mass, which are mounted on separate rails. This setup provides two advantages over crash sleds with so-called fixed specimen supports: (i) it allows for multiple independent measurements of the crush response using different instruments, and (ii) the specimen support can be varied and its reaction can be explicitly measured. This paper describes the experimental setup and data analysis methodology and illustrates the capability of the sled for measuring the specific energy absorption (SEA) of triaxially-braided carbon/epoxy composite C-channels and corrugated plates. The corrugated plate had a higher SEA than the C-channel and the SEAs did not vary when the striker mass and velocity were changed so that incident energy was constant.

Energy absorption↗